Field of the Disclosure
The present invention relates to a backlight unit and a liquid crystal display device (LCD) including the same. More particularly, the invention relates to a backlight unit and an LCD that fixes a bottom cover and a guide panel to prevent the guide panel from detaching outwards from the bottom cover.
Discussion of the Related Art
Generally, an LCD device displays images by adjusting light transmittance of liquid crystal using an electric field.
FIG. 1 is a cross-sectional view illustrating a non-light entering portion of a backlight unit of an LCD according to the related art.
Referring to FIG. 1, the LCD includes a liquid crystal panel 80, at least one optical sheet 45, a light guide plate 50, a reflection sheet 60, a bottom cover 30 and a guide panel 40.
In more detail, the liquid crystal panel 80 includes a thin film transistor (TFT) substrate, a color filter substrate, and a liquid crystal layer between the TFT substrate and the color filter substrate.
Polarization plates may be attached to bottom and top surfaces of the liquid crystal panel 80, respectively.
The light guide plate 50 functions to transmits light from a light source toward the liquid crystal panel 80, and is formed of plastic material such as PMMA (poly methyl methacrylate), or glass material.
The at least one optical sheet 45 is disposed on the light guide plate 50, and diffuses and concentrates light passing through the light guide plate 50 and supplies the light to the liquid crystal panel 80.
The reflection sheet 60 is disposed below the light guide plate 50, and reflects the light leaked from the light guide plate 50 back in the direction of the liquid crystal panel 80.
The bottom cover 30 has an accommodating space therein to accommodate the reflection sheet 60, the light guide plate 50 and the optical sheet 45.
A hook 30a is formed at a side surface of the bottom cover 30. The hook 30a protrudes outward through a Hemming process.
The guide panel 40 is adjacent to the light guide plate 50 and the optical sheet 45. The guide panel 40 includes a side surface portion that surrounds an outer surface of the bottom cover 30, and a supporting portion that extends from the side surface portion toward the light guide plate 50 and the optical sheet 45 and supports the light guide plate 50 and the optical sheet 45.
At least one first hole hl1 is formed at the side surface portion of the guide panel 40 and is coupled to the corresponding hook 30a. 
Through the coupling of the hook 30a in the bottom cover 30 and the first hole hl1 of the guide panel 40, the bottom cover 30 and the guide panel 40 are fixed to each other.
A binding force between the hook 30a and the first hole hl1 is weak. Thus, the hook 30a and the hole hl1 can be easily separated.
Further, a second hole hl2 is formed at a bottom surface of the supporting portion of the guide panel 40. Through the coupling of the second hole hl2 to an end of the side surface of the bottom cover 30, the hook 30a and the hole hl1 of the guide panel 40 can be separated. Thus, the guide panel 40 is shifted and the guide panel 40 will be separated from the end portion of the side surface of the bottom cover 30.
Further, the bottom surface of the supporting portion of the guide panel 40 contacts the optical sheet 45, and the liquid crystal panel 80 may be placed on a top surface of the supporting portion of the guide panel 40.
The top surface of the supporting portion of the guide panel 40 and the liquid crystal panel 80 may be fixed to each other using, for example, a double-sided adhesive tape.
Recently, along with lightweight and thin profile, the LCD is required to have a narrow bezel and a thin backlight unit to realize slim design of a final product such as for a TV or monitor. The bezel is defined as a width of a non-display region outside a display region.
In the related art LCD, to reduce the bezel, a first thickness d1 of the side surface portion of the guide panel 40 is required to be small, and also, a second thickness d2 of the supporting portion of the guide panel 40 is required to be small.
Accordingly, a depth d3 of the second hole hl2 is required to be small.
Accordingly, an extent to which the end of the side surface of the bottom cover 30 is positioned in the second hole hl2 is reduced. Thus the hook 30a of the bottom cover 30 and the first hole hl1 of the guide panel 40 are separated, and the guide panel 40 is bent outwards from the bottom cover. Therefore, a defect of the backlight unit is caused.